RU-2861464-C1 - METHOD FOR QUALITATIVE AND QUANTITATIVE DETERMINATION OF DETERGENT ADDITIVES IN MOTOR FUELS (VARIANTS)

RU2861464C1RU 2861464 C1RU2861464 C1RU 2861464C1RU-2861464-C1

Abstract

FIELD: chemical industry. SUBSTANCE: group of inventions relates to the field of quality control of motor fuels. Disclosed are methods (variants) for the qualitative and quantitative determination of nitrogen-containing detergent additives in motor fuels by changing the optical characteristics of the fuel, in which a buffer solution of an acid sulphophthalein dye is introduced into the analysed fuel, the resulting mixture is stirred, after phase separation, the upper hydrocarbon layer is separated, for qualitative analysis, the colour change is recorded, and for quantitative analysis, photometry is performed in the visible region of the spectrum at the wavelength of the absorption maximum of the reaction product of the dye and the additive, and the amount of the detergent additive is determined from a calibration graph. EFFECT: highly sensitive, selective and reproducible method for the qualitative and quantitative determination of concentrations of a wide range of nitrogen-containing detergent additives of various types in automotive fuels, ensuring maximum reliability and reproducibility of results while minimising the time and complexity of the determination, which should be implemented using simple and accessible laboratory equipment. 4 cl, 14 dwg, 8 tbl

Inventors

Fedoseeva Daria Dmitrievna
Karavai Vladimir Petrovich
Zolotov Aleksei Vladimirovich
KOTELEV MIKHAIL SERGEEVICH
Leshchev Sergei Mikhailovich

Dates

Publication Date: 20260505
Application Date: 20250801

Claims (4)

1. A method for the qualitative and quantitative determination of nitrogen-containing detergent additives in motor fuels based on changes in the optical characteristics of the fuel, comprising contacting the analyzed fuel with a color reagent capable of reacting with nitrogen-containing detergent additives, characterized in that a saturated aqueous buffer solution of an acid dye of the sulfophthaleine series at room temperature is introduced into the analyzed fuel in an equal volume ratio to the analyzed fuel, the resulting mixture is stirred to intensify the reaction between the dye in ionized form and the active ingredient of the nitrogen-containing detergent additive and the process of extraction of the colored complex product by the fuel, after separation of the phases the upper hydrocarbon layer is separated and the change in color is recorded for conducting a qualitative analysis, and for conducting a quantitative analysis photometry is carried out in the visible region of the spectrum at the wavelength of the maximum absorption of the product of interaction of the dye and the additive and the amount of detergent additive is determined according to a calibration graph.
2. A method for the qualitative and quantitative determination of detergent additives in motor fuels according to paragraph 1, characterized in that when using an acid dye of the sulfophthalein series, selected from the group of products bromophenol blue (BPS) and bromocresol green (BCG), the color change is recorded at a characteristic pH value in the range from 4.0 to 6.0, depending on the dye used; for the preferred BPS, the color change is recorded at a pH of 4.8-5.8 of its saturated aqueous solution with the addition of buffer components.
3. A method for the qualitative and quantitative determination of nitrogen-containing detergent additives in motor fuels based on changes in the optical characteristics of the fuel, comprising contacting the analyzed fuel with a color reagent capable of reacting with nitrogen-containing detergent additives, characterized in that a saturated aqueous solution of an acid dye of the sulfophthaleine series, at room temperature, is introduced into the analyzed fuel in an equal volume ratio to the analyzed fuel, diluted with a light hydrocarbon solvent selected from the group of hexane, heptane, octane, the resulting mixture is stirred to intensify the reaction between the dye in ionized form and the active ingredient of the nitrogen-containing detergent additive and the process of extraction of the colored complex product with the diluted fuel, after separation of the phases the upper hydrocarbon layer is separated and the color change is recorded for qualitative analysis, and for quantitative analysis photometry is carried out in the visible region of the spectrum at the wavelength of the maximum absorption of the product of interaction of the dye and the additive and the amount of detergent is determined additives according to the calibration graph.
4. A method for the qualitative and quantitative determination of detergent additives in motor fuels according to paragraph 3, characterized in that when using an acid dye of the sulfophthalein series, selected from the group of products bromophenol blue (BPS) and bromocresol green (BCG), the color change is recorded at a characteristic pH value in the range from 3.0 to 4.0, depending on the dye used; for the preferred BPS, the color change is recorded at a pH of 3.0, which is set automatically upon obtaining its saturated aqueous solution.

Description

Field of technology to which the invention relates The present invention relates to the field of quality control of motor fuels, in particular, to laboratory methods for determining the content of multifunctional detergent additives in motor gasolines and diesel fuels and can find application in analytical laboratories of petroleum product supply enterprises. State of the art Multifunctional detergent additives are an essential component of modern automotive fuels. Their inclusion in fuel formulations is necessary to prevent the formation of deposits in engine fuel systems, injectors, intake valves, combustion chamber surfaces, etc. These deposits are formed as a result of incomplete combustion of fuels containing significant amounts of aromatic and olefinic components, poor engine tuning, or the use of low-quality fuel. These deposits are associated with significant engine performance issues, such as affecting the air-fuel mixture and combustion efficiency, increasing fuel consumption, causing loss of power, and increasing emissions and exhaust toxicity. Thus, the introduction of multifunctional detergent additives allows us to produce fuels with improved performance properties, such as reduced tendency to form resinous deposits, and also ensure the cleansing of engine systems from previously formed deposits. Using fuels with such additives improves the reliability of fuel injection systems, maintains stable engine settings during operation, reduces fuel consumption and harmful emissions, and lowers vehicle maintenance costs. Verification of the presence and quantitative determination of detergent additives is necessary to control the process of introducing these products into fuels with improved performance and environmental properties, as well as to verify and monitor the additive content and compliance of the fuel's detergent properties with established requirements (which are typically included in the accompanying documentation) or other relevant specifications during shipment, transportation, storage, and sale. Consumers must rely solely on the integrity of their suppliers, as regulatory authorities cannot guarantee the presence of additives in fuel. Current regulatory and technical documentation for automotive fuels does not address the detection of detergent additives or their quantitative analysis, and there are no generally accepted methods. Therefore, the development of a highly sensitive, reliable, and easy-to-implement method for the qualitative and quantitative determination of detergent additives in automotive fuels is necessary. Most of the currently used detergent additives for motor fuels are based on high-molecular-weight nitrogen-containing derivatives, such as polyolefinamines, polyolefin-substituted succinimides or polyamine succinimides, Mannich bases of substituted phenols with aldehydes and mono- or polyamines, polyetheramines, and others. They are typically multifunctional packages that, along with detergents, contain various functional additives, such as carrier oils, corrosion inhibitors, antioxidants, metal deactivators, antistatic agents, friction modifiers, demulsifiers, solvents and diluents, and others (Robert D. Tack, Fuel Additives. Chemistry and Technology. First Edition. Published by John Wiley & Sons Inc, 2022, pp. 77-116). Multifunctional detergent additive packages demonstrate high efficiency at very low concentrations (typically less than 0.1% by weight). This is, on the one hand, an advantage, but at the same time, it makes determining the quantitative content of such additives, necessary for verifying fuel quality criteria, a very complex task. Furthermore, the fuel itself, as a complex matrix of chemical compounds, significantly complicates analysis. An analysis of scientific, technical and patent literature revealed technical solutions designed for the qualitative and quantitative determination of detergent additives in motor gasoline. Most proposed methods rely on complex, expensive laboratory equipment and labor-intensive analytical methods, such as infrared spectroscopy, chromatography (thin-layer, liquid, and gel permeation), mass spectrometry, thermogravimetry, and nuclear magnetic resonance spectroscopy. Samples often require relatively complex preparation procedures, and there are challenges with calibration or standardization, for example, when results depend on the type of base fuel being tested. While the aforementioned methods are accurate for classifying additive types, they are ineffective for their quantitative determination. At the same time, the supply of simple tests that can be used both in the laboratory and in the field for rapid detection and quantification is very limited (Zhi Wanwan et al., “Recent Advances in the Rapid Detection and Performance Evaluation Methods of Detergent Additives for Gasoline,” China Petroleum Processing and Petrochemical Technology Review, 2023, Vol. 25, No. 2, pp. 165-176). A known method for determining the presen